There is a way to get the Wii to run "homebrew" programs. One of them will take the Animal Crossing save file and copy it to the SD card. Once it is on the card, you can take it to your PC and change it. Someone wrote an AC town editor that will show you a map of your town with different colored dots for trees, flowers, buildings, etc. You can also change the layout of the river, cliffs, buildings. There is also a grass editor that will let you set a coverage value from 0 to 255 for every square. There is also a button that will simply set all squares to full grass. Once you are done, you put the save file back on the SD card, and load it back into the Wii.
That is the main reason I wanted to try editing the town. If we can just turn on grass, then we can put flowers where we want, rather than trying to cover every inch to regrow it.